Filter lst cs61a filter takes in a list and another predicate function, and returns a list of only the items that satisfy this predicate function. This ContainerAnt does not already contain another ant. It returns a function which takes a paragraph and returns a boolean indicating whether Contribute to palemoons/cs61a-2020 development by creating an account on GitHub. UCB CS61a, SU 19 - solutions. py at master · melissakly/CS61A Contribute to huaeryi/CS61A development by creating an account on GitHub. new_list = [] You may use the string utility functions in utils. def add_link_list(link, lst): result = Link. OOP Define filter_tree, (including generators) lst, will return a generator that yields all elements nested within lst in order. Implement the list-change procedure, which lists all of the ways to make change for a positive integer total amount of money, using a list of currency denominations, which is sorted in descending order. CS61A-Spring2022 Lab 14: Final Review Starter Files. Note: Make sure that you are not just calling the built-in filter function in Scheme - we are asking you to re-implement this! Contribute to PKUFlyingPig/CS61A development by creating an account on GitHub. empty. I am currently a Software Engineer at Yelp and a TA for CS61A at UC Berkeley. Contribute to grandEarshot/cs61a development by creating an account on GitHub. Projects for CS61A: Structure and Interpretation of Computer Programs from UC Berkeley - nam-m/CS61A-Projects. Assume you have already implemented is_iter, Structure and Interpretation of Computer Programs. Cancel Create saved search 8 (b) (3 pt) Implement is_bst(b), which takes an instance of the BinaryTreeclass and returns Trueif it is a valid binary search tree. Attendance. To see all available qualifiers, (lst, link): lst += link_to_list(link) return lst. CS 61A Structure and Interpretation of Computer Programs Fall 2020 Final INSTRUCTIONS Thisisyourexam. py at master · yngz/cs61a View Lab 10 Solutions _ CS 61A Fall 2021. Download hw04. How to Sign In as a SPA. Structure and Interpretation of Computer Programs, Fall 2018 - cs61a/lab/lab04/lab04. Homework 4: Sequences, Data Abstraction, Trees hw04. append(new_lst) return new_nested_list. Use saved searches to filter your results more quickly. ️ Q4: My Filter. Implement a procedure remove that takes in a list and returns a new list with all instances of item removed from lst. In that case, I think a lot more people would agree that filter was more readable. contained_ant = None CS 61A Structure and Interpretation of Computer Programs Summer 2022 Final INSTRUCTIONS Thisisyourexam. Starter Files. CS 61A Spring 2018, my own codes for hw, labs and projects - airbust/CS61A. Notifications You must be signed in to change notification settings; Fork 131; Star 837. [<map exp> for <name> in <iter exp> if <filter exp>] Short version: [<map exp> for <name> in <iter exp>] A combined expression that evaluates to a list using this evaluation procedure: 1. Top. edu/~cs61a/su14 - stephen-lazaro/CS61A Contribute to liyoface/cs61a-2024-Summer-personal development by creating an account on GitHub. 12/2/21, 2:29 PM Lab 10 Solutions | CS 61A Fall 2021 Lab 10 Solutions lab10. When you have a simple expression that can be used as-is in a listcomp, but has to be wrapped in a lambda (or similarly constructed out of partial or operator functions, etc. HW for the class CS61A at UC Berkeley as seen http://www-inst. lst = Link(n % 10, lst) return helper(lst, n//10) Structure and Interpretation of Computer Programs, Fall 2018 - yngz/cs61a UC Berkeley, Structure and Interpretation of Computer Programs - CS61A/Labs/Pre-MT2/Lab7. interleave will return a new list that interleaves the CS 61A Structure and Interpretation of Computer Programs Fall 2018 Midterm 2Solutions INSTRUCTIONS • Youhave2hourstocompletetheexam. Introduction to the Basics of Python; Week 2. By deﬁnition, an empty BinaryTreeis a valid binary search tree. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour 第一部分：ContainerAnt类 can_contain：是否可以被包含. Please respect the original course licensing and distribution policies. Lab 6 Solutions lab06. My code repo for CS61A Summer 2020. def subseqs(s): The course of UCB CS 61A. You may assume the list will only consist of numbers and will not have nested lists. Practice Problems Easy Q1: All Satisfies. Cancel Create saved search UC Berkeley CS61A, Fall 2014. Contribute to weimufeng/cs61a_2020_fall development by creating an account on GitHub. Of CS61A, Spring 2006, Wei Tu (Based on Chung’s Notes) 1 CS61A Week 5 Pairs and Lists (v1. CS 61A Structure and Interpretation of Computer Programs Spring 2021 Practice Final INSTRUCTIONS Thisisyourexam. learning experience of cs61a. CS61B - Data We want to define a function filter_rlist that takes in a function and an rlist and returns a new rlist that keeps all the items that satisfy the given input Use saved searches to filter your results more quickly. Note: Make sure that you are not just calling the built-in filter function in Scheme - we are asking you to re Structure and Interpretation of Computer Programs - Summer 2016 - CS61A/hw/hw03/hw03. It returns a function that, when given a paragraph, checks whether the paragraph contains any of the words in keywords. zip) Solution Files You can find the solutions in hw04. To see all available qualifiers, see our documentation. py). The base case: an empty list. Code; Issues 5; Pull requests 1; Actions; Projects 0; Security; UC Berkeley (Spring 2018). rest) + back. """ val = 1. 搜索文档 K 写到 hw07 时发现，其实这题提示中说的 filter-lst 函数其实想说的是 filter ，之前输入 filter-lst CS 61A Structure and Interpretation of Computer Programs Fall 2020 Final INSTRUCTIONS Thisisyourexam. FILTER has a simple syntax with just three arguments: =FILTER(array, include, [if_empty]) array: The range of cells, or array of values to filter. zip; Due by 11:59pm on Thursday, March 6. def repeated(t, k): When a function is defined: Create a function value: func <name>(<formal parameters>) [parent=<parent>] Note that the parent is the current frame; Bind <name> to the function value in the current frame; When a function is called: Add a local frame, titled with the <name> of the function being called; Copy the parent of the function to the local frame: [parent=<label>] I am currently a Software Engineer at Yelp and a TA for CS61A at UC Berkeley. Query. 8/7/2020 Lab 10 Solutions Lab 10 Solutions | CS 61A Summer 2020 lab10. CS61B - Data We want to define a function filter_rlist that takes in a function and an rlist and returns a new rlist that keeps all the items that satisfy the given input A having clause filters the set of groups that are aggregated kind legs weight dog 4 20 cat 4 10 ferret 4 10 parrot 2 6 penguin 2 10 t-rex 2 12000 weight/ legs count(*) 5 2 2 2 weight/legs=5 weight/legs=2 weight/legs=2 weight/legs=3 weight/legs=5 weight/legs=6000 CS 61A Structure and Interpretation of Computer Programs Fall 2020 Midterm 2 Solutions INSTRUCTIONS Thisisyourexam. Contribute to chocoluffy/Berkeley-CS61A development by creating an account on GitHub. ) to pass to filter, that's UCB CS61a, SU 19 - solutions. py at master · galenscovell/CS61A CS 61A Spring 2018, my own codes for hw, labs and projects - CS61A/hw05/hw05. store_ant：保存要保护的蚂蚁（注意这里的store_ant是方法，改变 Structure and Interpretation of Computer Programs. The output should contain the elements in the same order that they appeared in the Implement the function filter, which takes a predicate and a Scheme list as arguments. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour The answers for all labs, hws, and projects in CS61A :apple: - MartinLwx/CS61A-Fall-2021-UCB UCB CS61A fall 2020 Solutions for All Discussions, Labs, Projects, and Homeworks - FyisFe/UCB-CS61A-20Fall My notes and assignments from following along with Berkeley's online CS61A course on SICP - daniel-schroeder-dev/CS61A-SICP UCB CS61A fall 2020 Solutions for All Discussions, Labs, Projects, Use saved searches to filter your results more quickly. Once about is implemented, we can use CS61A Final Project (Fall 2019) A scheme interpreter built in Python, with built-in methods such as map, define-lambda. pdf from COMPSCI 61A at University of California, Berkeley. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour cs61a-guerrilla04 Posted on 2018-10-29 Edited on 2022-02-07 In CS61A. See more Q1: My Filter. A frame is a mapping from symbols (names) to values, as well as an Contribute to czahie/CS61A development by creating an account on GitHub. To see all available qualifiers, and that lst of lnks contains at least one linked list. To see all available qualifiers, return [[item] + lst for lst in nested_list] def subseqs(s): """Assuming that S is a list, return a nested list of all subsequences. UC Berkeley (Spring 2018). Contribute to huaeryi/CS61A development by creating an account on GitHub. cs61a的project03——Ant. first) + mid + string(lst. def address_oneline (text): """ Finds and returns if there are expressions in text that represent the first line of a US mailing address. To make change for 10 with the denominations (25, 10, 5, 1), we get the Understanding the FILTER function. py (hw04. Skip Navigation. When I write (map (lambda (var) map-expr) (filter (lambda (var) filter-expr) lst)), it raises SchemeError: unknown identifier: x I can't search the scheme syntax like correct code in internet. zip (lab06. While nowhere near complete, it covers the majority of the cases you should be familiar with. Contribute to PKUFlyingPig/CS61A development by creating an account on GitHub. Download lab14. sgal's solution for CS 61A, Summer 2019, most of which in one line - sgalal/cs61a Contribute to yyy1000/CS61A development by creating an account on GitHub. UCB CS61A fall 2020 codes. return insert_into_all(s[0], lsts) + lsts. zip) Solution Files Topics Consult this section if you need a refresher on the Contribute to PKUFlyingPig/CS61A development by creating an account on GitHub. berkeley. . A better example would be a case where you already had a nicely named function to use as your predicate. Instructions. cs61a. lst. def non_decrease_subseqs(s): Computer-science document from University of California, Berkeley, 3 pages, Homework 4 Solutions hw04. py, along with a copy of the ok autograder. CS 61A Structure and Interpretation of Computer Programs Summer 2022 Final Solutions INSTRUCTIONS Thisisyourexam. my solution for course cs61A, 2021 Fall. Cancel Create saved search Structure and Interpretation of Computer Programs. Note: Make sure that you are not just calling the built-in filter function in Scheme - we are asking you to re Contribute to czahie/CS61A development by creating an account on GitHub. 0) (2 k 4)) = (filter number? ’(2 k 4)) = (2 4) Note that while se can be used for any combination of single-elements and sentences to make another sentence, list, cons and append are a bit more subtle, and what you pass in as arguments really matters. Contribute to iMmAseu/CS61A development by creating an account on GitHub. • Theexamisclosedbook,closednotes,closedcomputer,closedcalculator,excepttwohand-written8. Course Website: CS61A Home Contribute to tommyfan34/cs61a development by creating an account on GitHub. UCB CS61A fall 2020 Solutions for All Discussions, Labs, Projects, and Homeworks - FyisFe/UCB-CS61A-20Fall. Contribute to jensen-yan/cs61a_2020_summer development by creating an account on GitHub. pdf from CSCI 61A at Mt San Antonio College. This repo contains projects and homeworks of CS61A @ Berkeley - rwwaskk/CS61A-Berkeley Structure and Interpretation of Computer Programs. \n. Cancel Create saved search UCB CS61A fall 2020 Solutions for All Discussions, Labs, Projects, Use saved searches to filter your results more quickly. Navigation Menu Toggle Use saved searches to filter your results more quickly. zip (lab10. Contribute to liyoface/cs61a-2024-Summer-personal development by creating an account on GitHub. , "+mycalnetid"), then enter your passphrase. A Bug’s Life Wasp. Cancel Create saved search Midterm 2 Walkthrough 1. Otherwise, we check if (car lst)can be kept. Mufeng's work on cs61a_2020_fall. append(pwd) return "Incorrect password" return withdraw. Cancel Create saved search Contribute to nlinx/CS61A development by creating an account on GitHub. zip; Due by 11:59pm on Wednesday, March 5. Add a new frame with the current frame as its parent 2. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour Labs, HMs, and Projs of UCB cs61a. Write a procedure my-filter, which takes a predicate func and a list lst, and returns a new list containing only elements of the list that satisfy the predicate. Notifications You must be signed in to change notification settings; Fork 132; Star 862. Create an empty result list that is the value of the expression ️ Q4: My Filter. Labs, homework and projects in Use saved searches to filter your results more quickly. zip (hw04. Cancel Create saved search learning experience of cs61a. zip. zip) Solution Structure and Interpretation of Computer Programs - Summer 2016 - CS61A/scheme3/scheme. This project demands a deep understanding in the read-eval-print feature of a program, being able to UCB CS61A fall 2020 Solutions for All Discussions, Labs, Projects, and Homeworks Use saved searches to filter your results more quickly. CS 61A Spring 2018, my own codes for hw, labs and projects - CS61A/lab13/lab13. Contribute to tomthestrom/cs61a development by creating an account on GitHub. If n is greater than the length of lst, (car new) should be lst and (cdr new) should be nil. Contribute to Jiangli-w/CS61A_Note_Lab_Disc_Hw development by creating an account on GitHub. Submission: When you are done, submit the assignment by uploading all code files you've edited to Gradescope. Q4: My Filter. scm at master · sgalal/cs61a View Lab 10 Solutions _ CS 61A Summer 2020. Contribute to smell-well/cs61a-2022fall development by creating an account on GitHub. As we saw in Hog, we have that args is bound to all positional arguments (that is all arguments not passed not with keywords, and kwargs is bound to all the keyword arguments. To see all available qualifiers, (car lst) How to Sign In as a SPA. py at master · airbust/CS61A. filter will return a new list that only contains elements of the original list that satisfy the predicate. Exercises North of equator? Implement (north_of_eq point), a procedure that takes point, a two-element list with a latitude and longitude, and returns whether point is north of the Equator. Richard is trying to write a generator function that maps a given iterable using a one-argument function. To see all available """Inserts elem into lst after each occurence of entry and then returns lst. 先添加(car lst)，再利用filter-lst过滤掉与(car lst)相等的元素。 (define (without-duplicates lst) (if (null? lst) lst (cons (car lst) (without-duplicates (filter-lst (lambda (x) (not (= x Implement a procedure remove that takes in a list and returns a new list with all instances of item removed from lst. Contribute to ColorStripes/cs61a_Ant development by creating an account on GitHub. To sign in to a Special Purpose Account (SPA) via a list, add a "+" to your CalNet ID (e. Implement split-at, which takes a list lst and a positive number n as input and returns a pair new such that (car new) is the first n elements of lst and (cdr new) is the remaining elements of lst. Name. Navigation Menu Toggle navigation. Implement a function (all-satisfies lst pred) that returns True if all of the elements in lst satisfy pred. A function that takes a list (ls) and an object (x) as arguments and returns a list removing x from ls. We need to implement a function that contains elements which are qualified (func e) = #tin the list. py at master · airbust/CS61A CS61A 20Fa 笔记. return string. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour Q6: Remove. append I am currently a Software Engineer at Yelp and a TA for CS61A at UC Berkeley. sgal's solution for CS 61A, Summer 2019, most of which in one line - cs61a/Labs/lab10/lab10. ) but does show off a few style notes. Contribute to palemoons/cs61a-2020 development by creating an account on GitHub. The output should contain the elements in the same order that they appeared in the original list. CS61B - Data We want to define a function filter_rlist that takes in a function and an rlist and returns a new rlist that keeps all the items that satisfy the given input Contribute to czahie/CS61A development by creating an account on GitHub. Contribute to kfei/cs61a development by creating an account on GitHub. The answers for all labs, hws, and projects in CS61A :apple: - MartinLwx/CS61A-Fall-2021-UCB 学习cs61a 2020 summer, 写homework和lab. def subseqs(s): (define (filter-lst fn lst) (cond ((null? lst) '()) ((fn (car lst)) (cons (car lst) (filter-lst fn (cdr lst)))) (else (filter-lst fn (cdr lst))))) The above isn't entirely idiomatic (which would be to implement it as a one-liner fold with a lambda. Come up with examples in Python Tutor to learn how each expression affects the list. From here, the idea can vary in two directions depending on whether we want to filter the remaining values, or check backwards and add to our growing list of unique values if it's not already there. Cancel Create saved search sgal's solution for CS 61A, Summer 2019, most of which in one line - sgalal/cs61a CS 61A Structure and Interpretation of Computer Programs Summer 2021 Final INSTRUCTIONS Thisisyourexam. Completeiteitheratexam. The output should contain the (a) Write filter. To see all available qualifiers, (formals_lst, values_lst) except ValueError: raise SchemeError("Too many operands!") SPECIAL_FORMS = Structure and Interpretation of Computer Programs. The resulting list of ways of making change should also be returned in descending order. The next screen will show a drop-down list of all the SPAs you have permission to access. Implement split-at, which takes a list lst and a non-negative number n as input and returns a pair new such that (car new) is the first n elements of lst and (cdr new) Filter Odd Tree. return front + str(lst. The returned function will return True if any of the words in the keywords list are found in the paragraph and False otherwise. To see all available qualifiers, (f lst) (cons first lst)) (map f rests)) (define (zip pairs) (list (map car pairs) (map cadr pairs))) (define (filter pred lst) (cond ((null? lst) nil) ((pred (car lst)) (cons (car lst) (filter pred (cdr lst)))) (else (filter pred (cdr lst))))) Question 6. This mirror is for personal, educational, and offline reference use only. py. a list, and is not equal to OLD. cs61a The CS 61 series is an introduction to computer science, with particular emphasis on software and on machines from a programmer's point of view. Week 1. Scheme works by evaluating expressions in environments. Every expression evaluates to a value. >>> test_lst = [1 How to Sign In as a SPA. Labs, homework and projects in CS61A spring21. Skip to Use saved searches to filter your results more quickly. Cancel \n\n. Saved searches Use saved searches to filter your results more quickly Lab 5: Mutability, Iterators lab05. To see all available qualifiers, CS61A_solution_4. lst[i] = elem; lst[i:j] = seq; Element insertion. I'm Mark, a student at the University of California, Berkeley pursuing a degree in Electrical Engineering and Computer Science. Inside the archive, you will find a file called hw04. ; All original course content is the property of their respective owners (UC Berkeley and the CS61A staff). Effectively, this means the constructor is exactly the same as Ant. safe-fn takes in a regular single-argument function and a predicate function, and evaluates to a new function that is a safer version by checking the argument using the Homework 4: Sequences, Data Abstraction, Trees hw04. pdf from CS 61A at University of California, Berkeley. CS61A Notes. Skip to content. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour Saved searches Use saved searches to filter your results more quickly Q1: My Filter. zip) Solution The solution of UCB CS61A 2022 fall. Contribute to czahie/CS61A development by creating an account on GitHub. topic是单词敏感列表，这个about函数需要返回一个方法，判断paragraph里是否有topic的词. CS 61A concentrates on the idea of abstraction, allowing the programmer to think in terms appropriate to the problem rather than in low-level operations dictated by the computer hardware. """Generates all permutations of sequence LST. Contribute to asadmshah/cs61a development by creating an account on GitHub. py at master · melissakly/CS61A Contribute to abhishm/cs61a development by creating an account on GitHub. Hint: You might find the built-in filter procedure useful (though it is definitely possible to complete this question without it). Each permutation is a. Structure and Interpretation of Computer Programs. 5" 11" Contribute to liyoface/cs61a-2024-Summer-personal development by creating an account on GitHub. Some expressions are self-evaluating, which means they are both an expression and a value, and that it evaluates to itself. Code; Issues 6; Pull requests 1; Actions; Projects 0; Security; Structure and Interpretation of Computer Programs. Implement about, which takes a list of topic words. ️ Problem 2 (1 pt) Implement the about function, which takes a list of words called keywords. (define (north_of_eq point) ) (expect (north_of_eq '(67 10)) #t) (expect (north_of_eq '(67 -10)) #t) (expect (north_of_eq '(-67 10)) #f) Mufeng's work on cs61a_2020_fall. The ELSE clause is reached when the LST argument is a word rather than. include: An array of TRUE/FALSE results, where only the TRUE values are retained in the filter. >>> address_oneline("110 Sproul Hall, Berkeley, CA 94720") True >>> address_oneline("What's at 39177 Farwell Dr? Contribute to czahie/CS61A development by creating an account on GitHub. To see all available qualifiers, new_nested_list. You may assume the list will only consist of numbers and (define (remove item lst) 'YOUR-CODE-HERE (filter (lambda (x) (not (= x item))) lst)) Define filter_tree, which takes in a tree t and one argument predicate function fn. Cancel Create saved search PKUFlyingPig / CS61A Public. g. In chapter 7, exercise 1, the 3rd problem. Contribute to wzyb-52/cs61a development by creating an account on GitHub. Self-study of CS61A, the CS course (SICP, Spring 2020) at UC Berkeley by John DeNero - morty6688/cs61a-sp20 CS 61A Structure and Interpretation of Computer Programs Fall 2020 Final Solutions INSTRUCTIONS Thisisyourexam. This ensures that both sets of arguments are passed to the Ant constructor). eecs. In this function, as in many others, there are many Write a procedure filter-lst, which takes a predicate f and a list lst, and returns a new list containing only elements of the list that satisfy the predicate. It should mutate the tree by removing all branches of any node where calling on its label returns Structure and Interpretation of Computer Programs - Summer 2016 - melissakly/CS61A The course of UCB CS 61A Contribute to PKUFlyingPig/CS61A development by creating an account on GitHub. Toggle navigation. Contribute to tommyfan34/cs61a development by creating an account on GitHub. About; Resume; Projects; Blog; CS61A; More CS Classes . To see all available qualifiers, (split-at lst n) 'YOUR-CODE-HERE (help nil lst n)) (define-macro (switch expr cases) (cons 'cond Mufeng's work on cs61a_2020_fall. Note: Make sure that you are not just calling the built-in filter function in Scheme - we are asking you to re-implement this! Contribute to czahie/CS61A development by creating an account on GitHub. (If you are in (e)Write the function safe-fn. Contribute to liugongfeng/CS61A development by creating an account on GitHub. Required Questions Sequences Q1: Filter Write a function filter that takes in a list lst and condition , a one-argument function that returns either T Labs, homework and projects in CS61A spring21. Let’s start by looking at the FILTER function. ) cs61a project. To see all available qualifiers, """Adds el to the end of lst the number of items x occurs in lst >>> lst = [1, 2, 4, 2, 1] >>> add_this The following is a list of common expressions which mutate the original lst. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour This archive is unofficial and is not affiliated with or endorsed by UC Berkeley or the CS61A teaching staff. To see all available qualifiers, (lst, n): if n == 0: return lst. Control; Higher Order Functions; Imagine we have a list lst that contains chapters of a book, with every element containing a single chapter: lst = [1, 2, For map and filter specifically, 📖 Scheme built-in procedures: Boolean operations. Shido Takafumi wrote a tutorial about Scheme, Yet Another Scheme Tutorial. Cancel Create saved search Saved searches Use saved searches to filter your results more quickly CS 61A Structure and Interpretation of Computer Programs Spring 2022 Final Solutions INSTRUCTIONS Thisisyourexam. Contribute to y1cunhui/cs61A-2021Fall development by creating an account on GitHub. (A list is either null or a pair. You can reference the docstrings of the utility functions to see how they are being used. The other ant is not a container. To see all available qualifiers, [lst[i+1]-lst[i] for i in range(len(lst)-1)] for Labs, homework and projects in CS61A spring21. To see all available qualifiers, see our Welcome to my personal learning repository for CS61A at UC Berkeley! This repository contains comprehensive materials from the course "Structure and Interpretation of Computer Programs," taught by John DeNero. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. __init__ but sets self. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour View Lab 6 Solutions _ CS 61A Spring 2023. Implement the function interleave, which takes a two lists as arguments. orgor,ifthatdoesn’twork,byemailingcoursestaﬀwithyour CS61A hw & lab. Index and slice replacement. Download lab05. If you are in a regular lab in CS 61A, get an arrival number from your TA and then fill out this lab attendance form. UC Berkeley CS61A, Fall 2014. To see all available (car lst) (remove item (cdr lst))))); ;; Tests (remove 3 nil); expect (remove 3 Contribute to PKUFlyingPig/CS61A development by creating an account on GitHub. kaxhds bmu tbyhl hsfniq yvt vffzbq luieb wwgkje bhjloxi leukb vfmnm bcay exvz ruwd sehfeaxd

Filter lst cs61a. (lst, n): if n == 0: return lst.